1. Field of the Invention
The present invention relates to a developing unit used in an image forming device such as a copy machine, a printer and a facsimile machine for adhering a developer on an electrostatic latent image and developing the electrostatic latent image, and to an image forming device having the developing unit.
2. Description of the Related Art
In the above-described image forming device, when developing an electrostatic latent image, a bias voltage is impressed or a voltage is impressed for charging a developer (toner). An electrical wiring becomes necessary for the impressing operation. As an example of such a wiring, according to a first conventional image forming device, a bias electrode consisting of a piano wire, a stainless steel wire for a spring, a phosphor bronze wire or the like is provided on a sleeve flange. One end of the bias electrode is formed in a coil spring shape and makes contact with an electrode plate. According to a second conventional image forming device, a coil spring is used for feeding a bias voltage to developer charging members provided on both end parts of the developer carrier in a longitudinal direction. In case the developing unit can be inserted into or removed from the image forming device, an electrode for an outer connection is provided in a developing unit for feeding the voltage from the image forming device. Conventionally, an electrode consisting of a leaf spring is used.
By the wiring structure processed into the coil spring shape used in the first conventional image forming device, an attaching method is difficult. According to the second conventional image forming device, a structure for inserting in the coil spring becomes necessary, and a place where the coil spring can be used becomes limited. In addition, a sheet metal processing becomes necessary for the electrode structure formed by the leaf spring and the manufacturing costs increase.